Meet the heroes of your immune system

We talk about immunity as if it’s an army inside our body that’s ready to do battle with any infection that dares to cross its path. We try to eat the right foods to boost its numbers and are more prone to invasion when its numbers are low.

While that’s all most of us understand about immunity, a group of Australian researchers have made a huge discovery that could bolster the body’s immune defences and significantly lower the rate of autoimmune conditions.

Meet your MAIT cells

They’ve discovered the special opps of our immune system – the mucosal-associated invariant T cells, or MAIT cells. Generally, T cells are white blood cells that act as that military group we picture in our bodies, seeking out and destroying foreign invaders. MAIT cells are even more powerful.

Professor Jamie Rossjohn, of Monash University’s department of biochemistry and molecular biology in Melbourne, has been studying immunology for two decades. His team, together with scientists from the universities of Melbourne and Queensland, has discovered the role that MAIT cells play.

“They make up 10 per cent of all your T cells in the body and up to 45 per cent in the liver, but we never knew their function,” Rossjohn says. “Now we know they’re our first line of defence and recognise bits ofriboflavin [vitamin B2] that are given off by invading bacteria and fungi.” This means it’s now possible to track what they “see” inside the body.

New dawn for immunity

While the importance of these MAIT cells in the immune response was discovered two years ago, there have been more breakthroughs since then. The team of scientists also published a paper in April that revealed they’d identified the biomedical key that wakes up these MAIT cells and triggers them to respond.

To put this into perspective, the knowledge is so new it isn’t yet included in any scientific textbooks, let alone known commonly in the medical community.

“We’re at the tip of the iceberg to understanding what these MAIT cells can do and will be able to make some important discoveries in the next five to 10 years,” Rossjohn says. “We had no idea what 10 per cent of people’s immune systems were doing. Now we’ll be able to understand how these MAIT cells are activated and, most importantly, how they can protect us.”

What this means for you

While Rossjohn and his colleagues can’t inject us with a MAIT-cell boosting inoculation just yet, they’re trying to work out how different diseases cause these cells to act. For example, they already know that irritable bowel syndrome, ulcers, tuberculosis, thrush and even autoimmune conditions such as coeliac disease are implicated. Eventually their aim is to get that all-important biomedical “trigger” to set the MAIT cells into action and even form part of a protective vaccine. However, the activity of MAIT cells is only related to diseases caused by bacteria, not viruses, which means that illnesses such as the commoncold and flu won’t benefit.

Rossjohn says another goal is for MAIT cells to become a routine part of diagnosis, such as a blood test where a higher number of cells might indicate an internal imbalance.